Re: Remove configure --disable-float4-byval and --disable-float8-byval

On 2019-11-01 15:41, Robert Haas wrote:
> On a related note, why do we store typbyval in the catalog anyway
> instead of inferring it from typlen and maybe typalign? It seems like
> a bad idea to record on disk the way we pass around values in memory,
> because it means that a change to how values are passed around in
> memory has ramifications for on-disk compatibility.

This sounds interesting.  It would remove a pg_upgrade hazard (in the 
long run).

There is some backward compatibility to be concerned about.  This change 
would require extension authors to change their code to insert #ifdef 
USE_FLOAT8_BYVAL or similar, where currently their code might only 
support one method or the other.

> rhaas=# select typname, typlen, typbyval, typalign from pg_type where
> typlen in (1,2,4,8) != typbyval;

There are also typlen=6 types.  Who knew. ;-)

>   typname  | typlen | typbyval | typalign
> ----------+--------+----------+----------
>   macaddr8 |      8 | f        | i
> (1 row)

This might be a case of the above issue: It's easier to just make it 
pass by reference always than deal with a bunch of #ifdefs.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services